Lubricating grease compositions containing a salt of an alicyclic acid



Patented Nov. 28, 1961 3,010,901 LUBRICATRNG GREASE COMPOSITIONS CON- TAINIYG A SALT OF AN ALICYCLIC' ACID Arnold J. Moi-way, Clark, and Jeffrey H. Bartlett, New

Providence, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Dec. 12, 1958, Ser. No. 779,857

g 3 Claims. (Cl. 252-39) This invention relates to lubricating oil compositions and oil thickeners. Particularly, it relates to a lubricating oil composition containing a metal salt of an alicyclic acid. More particularly, the invention relates to'a grease which has been thickened with a mixed-salt type of grease thickenercontaining a salt of an alicyclic acid.

While the salts of the alicyclic acid of the invention may be used as the sole thickening agent, it is preferably used in combination with other salts, i.e. in the form of a mixed-salt thickener. Mixed-salt grease thickeners of low molecular weight acid in combination with intermediate and/or high molecular weight fatty acids are known. It has now been found that excellent mixed-salt thickened greases may be prepared in which an alicyclic acid is substituted for all, or at least a part, of the high and/or intermediate molecular weight fatty acid generally used in preparing mixed-salt type thickeners.

The mixed-salt thickeners of this invention will therefore be formed from the metal salts of one of the following combinations of acids:

(a) Low molecular weight acid and high molecular weight acid.

(b) Low molecular weight acid and an intermediate molecular Weight acid.

(c) Low molecular weight acid, intermediate molecular weight acid, and high molecular weight acid.

The high molecular weight acids which are used are alicyclic acids or mixtures of alicyclic acids and fatty acids.

The alicyclic acids useful in this invention are those monocarboxylic acids containing about to 16 carbon atoms per molecule. They may be prepared by caustic fusion of unsubstituted, saturated cyclic monoketones containing about 5 to 8 carbon atoms in the ring; examples of which are: cyclopentanone, cyclohexanone, cycloheptanone, and cyclooctanone. The fusion process involves an aldolization reaction followed by opening of the alicyclic ring possessing the remaining carbonyl group, the number of carbon atoms in the ring being generally the same as in the original ketone, with an equal number of carbon atoms in the side chain. Although it is conceivable that in some cases an 'isomerization could take place in which the ring may become a 5 or 6 membered ring when using the C or C cyclic ketone. The fusion reaction is preferably cairied out at about 275 to 325 C. for about A to 5 hours. At lower temperatures the rate of reaction and the yield are lower, while temperatures above 325 products. The caustic material used in the fusion will generally be sodium hydroxide or potassium hydroxide or mixtures thereof. The fusion reaction may be carried out in situ in the lubricating oil with other acids present C. result in lower molecular weight to directly form the desired mixed salt thickener. Or the alicyclic acid may be separately preformed. In the latter case, about 0.5 to 3 moles of the alkali is used per mole of the cyclic ketone. Using cyclohexanone as an example, then according to the article by E. L. Pelton, C. I. Starnes and S. A. Shrader in J.A.C.S., 72, 2039 (1950),

l-cyclo- 3 hexene-l-caproic acid is formed by fusion, as illustrated by the following equation:

H 0 CH2 A 2 H20 CH2 N CHzCHzCHzCHzCHZCOOH When the alicyclic acidis preformed, it is desirable to prepare it in an inert solv carbon oil having a boilin ent medium such as a hydrog point of 275 C. or higher.

After the reaction is completed, the reaction mass may then be added to water and the solvent removed by ex traction with a light naphtha such as petroleum ether,

pentane, hexane, etc. The

aqueous layer remaining from used in combination with the alicyclic acids described above, are the saturated and unsaturated, unsubstituted or hydroxy substituted fa used in the art for prepari eral, these fatty acids have from about 12 to 30 atoms, e.g., have saponification values Naturally occurring fatty tty acids that-are commonly ng grease thickeners. In gencarbon 12 to 24 carbon atoms, per molecule and of from about 150 to 300. acids, such as fish oil acids,

tallow acids, coconut oil acids, etc., may alsobe utiliZed either directly or preferab ly after hydrogenation to decrease any undesirably high degree of unsaturation. Mixtures of these high molecular weight fatty acids, e.g.

hydrogenated fish portion, are also operable,

oil acids with oleic acids, in any proas are fatty acid fractions obtained by distillation, extraction, or crystallization.

The intermediate molecular weight acids which may be used are those straight-chain saturated aliphatic, monocarboxylic hydrocarbon fatty acids having from about 7 to 10 carbon atoms.

Suitable low molecular Weight acids include saturated and unsaturated aliphatic acids having about 1 to 6 3, and their hydroxy derivatives.

acids may also be substitu molecular weight organic a hydrocarbon monocarboxylic carbon atoms, preferably l'to Also, inorganic mineral ted for all or part of the low cid.

The metal component of the mixed-salt thickener will generally be an alkali met al or an alkaline earth metal,

which metals may be used in the form of their bases, such as the oxides, hydroxides, or carbonates to neutralize the above-mentioned acids.

The lubricating oil portion of the grease may be either a mineral lubricating oil or a synthetic lubricating 'oil.

The compositions of the invention will comprise a major proportion of a lubricating oil and a minor thickening amount, say about 5 to 40,e.g. 15 to 30, .of the metal salt of the alicycli thickener.

c acid, or of the mixed-salt The mixed-salt grease thickener, in turn, will be formed from about 1 mole of the high and/orintermediate molecular weight acids with about 3 I015 moles, e.g. 5 to 12 moles, of the low molecular weight acid. The high molecular weight acid, in

alicyclic acid or it may consist combination with a high said combination being in percent of alicyclic acid to turn, may consist only of the of the alicyclic acid in molecular weight fatty acid, any ratio, e.g. 15 to wt. 85 to 15 wt. percent of fatty tion with high and intermediate molecular weight acids in which at least part of said high molecular weight acid consists of the alicyclic acid.

The final grease composition may also contain various additives, such as inhibitors, dyes, metal deactivators, corrosion preventors, deodorants, and so forth, as will be uuderstod by those skilled in the art.

The grease will generally be prepared by forming a mixture of acids or of acids and the cyclolretone in mineral oil, then reacting the mixture with a metal base, followed by heating the mixture for a time and temperature sufficient to form the complex thickener. Usually, the

mixture will be heated to temperatures of about 400 to 600 F., e.g. 420 to 500 F., and maintained there for a period of about /2 to 6 hours, erg. 1 to 4 hours depending on the size of the batch.

The invention will be vfurther understood by the following illustrations which include the preferred embodiments of the invention.

PREPARATION'OF ALICYCLIC FATTY ACID FROM CYCLOHEXANONE 'A one-gallon nickel reactor equiped with a stirrer, thermometer, feed line and condenser, was charged with 400 g. :of Primol D which is an inert white oil, 555 g. NaOI-I and 500' g. KOH. The mixture was heated to a temperature of about 300 to 310 C. and maintained at this temperature while 1,735 g. of cyclohexanone was added over a period of about 40 minutes. The tempera- I ture was maintained at 300 to 310 C. for another hour.

*Then the heat was turned off and the mixture wasallowed to. cool to 280 C. at which point the product was removed by suction. The 2,774 g. of reaction product thus obtained was poured into 9 liters of water, and was then extracted 3 times with petroleum ether using approximately 2.5 liters of petroleum ether for each extraction. These extracts on evaporation left a residue of 411 g. which consisted chiefly of the Primol D.

The aqueous layer from the above extraction was.

acidified with concentrated HCl (37% H01). The resulting acid was separated and dried to give a yield of 1615 g. of crude acids having an acid number of 254 mg. KOH per gram of crude acid. A 1,000 g. portion of the crude acid wasidistilled in a short path still at 0.3

mm. Hg pressure with the followingdata obtained:

Vapor V Bromine Neutrali- Cut No. Temp, Amount No, Cg. zation G. (g.) Bin /g. mg.

KOH/g.

1 Initial boiling point. 1 The 108 grams bottom fraction remaining contained some soap, so was acidifiedand extracted with ethyl other which on evaporation left a residue of 92 g. having the neutralization number of 219.2.

There was some petroleum ether in the crude acids charged to the still as 34 g. was collected in a Dry Ice proximately 5% of C acid was produced (i.e. cut No. 1)

a d better than 80% of the C alicyclic acid was obthis 4? tained (cuts 2 to 6). Cut 7 and the extracted bottom fraction contained substantial amounts of the C alicyclic acid, but were contaminated by higher molecular weight materials as indicated by their lower neutralization number.

Example I The alicyclic acid obtained above (cut 4) was then used, without further purification, in preparing a grease of invention having the following formulation:

Formulation: Percent weight 1 Fatty acid mixture approximating stearic acid in degree of unsaturation and molecular weight.

2 Cut 4, prepared as previously described. I

PREPARATION The grease was prepared by charging the Hydroiol Acids 51' and mineral oil to a fire heated kettle. This mixture was then warmed to P. Then, a blend of the acetic acid and the alicyclic acid was added, followed immediately by adding the sodium hydroxide in an aqueous solution (40% NaOH, 60% E 0). The mixture was then heated to a final temperature of 500 F. over a period of about /2 hour, and maintained at 500 F. for another /2 hour. The heat was then turned off, and the mixture was cooled to 200 F., at which point, phenyl rx-naphthylamine was added as an oxidation inhibitor. The grease wasthen homogenized by passing through a Gaulin homogenizer, operating at 6000 p.s.i. and finally cooled to room temperature.

Example 11 A second grease was prepared having the following composition:

PREPARATION The Hydrofol Acids 51, cyclohexanone and the mineral oil were charged to a fire heated kettle and warmed to 130 F. Then the acetic acid was added, followed by the addition of sodium hydroxide as an aqueous solution (40% NaOH, 60% H O). The temperature of the mixture was raised over a period of an hour to 500 F., and then further heated to a maximum temperature of 600 F. in another 20 minutes. The heat was turned off and the mixture was then cooled to 180 F., at which point the phenyl a-naphthylamine was added. The mixture was then passed through a Gaulin homogenizer, operated at Example III A third grease was prepared as follows:

Formulation: Percent weight Glacial acetic acid 12.0

Coconut fatty acids (60% caprylic acid, 40%

capric acid) 4.8 Acid from fusion of cyclohexanone 1 1.2 Hydrated lime 9.8 Phenyl d-naphthylamine 1.0

Mineral lubricating oil of 5S SUS. at 210 F 71.2 1 Cut 4, prepared as previously described.

PREPARATION The lime and mineral oil were added to a kettle and mixed to form an intimate slurry. Then a mixture of the acids were added and the total mixture was stirred for minutes. The mixture was then heated to 450 F. over a period of about 2 hours, and maintained at 45 0 F. for about /2 hour, followed by cooling to 180 F., at which point, the phenyl a-naphthylamine was added. The grease was passed through a Gaulin homogenizer, operating at 6000 p.s.i., and then cooled to room temperature.

The following table shows the physical properties of the greases of Examples I, II and III.

TABLE I Examples Properties I II III Appearance Excellent- Excellent. Excellent. Dropping Point, F 500+ 500+ 500+. Penetration, 77 F., mmJlO Unworked 285. Worked 60 strokes 300. Worked 100,000 strokes 3 10. Water Solubility:

below 150 F Insoluble Insoluble Insoluble. above 150 F So1uble Insoluble. Boiling Water Insoluble. Norma Hofimann Oxidation:

Hours to 10 p.s.i. drop 100+ Hours to 5 p.s.i. drop 400+. Lubrication Life (Hours) at 250 F.10,000 r.p.rn. 4,160+ 4,800+ 2,000+.

Temperature Rise above ambient F. 15 F 100 F? Timken EP Test, Load Oarried 45 lbs.

(narrow sear). Shell 4-Ball Wear Spot (mm. dia.) 0.27

8,5300 r.p.m.10 kg.l Hr.75

l Returned within 1 hour to ambient temperature.

2 Does not return to ambient, but stabilizes out at ISO-190 I a ABEO-NLGI Spindle Test.

While Examples I, II and 111 all represented excellent greases, the products of Examples I and II were very exceptional in that in actual lubricating use in anti-friction bearings operated at high speeds, they initially gave extremely low bearing temperature rise and had a low starting torque. -In fact, the temperature of the bearings returned to room temperature within an hour. These features are extremely important in industry since they allow the use of smaller horsepower motors, save on power, and allow the motors to run cooler, thereby prolonging the life of both the motor and lubricant.

While the preceding examples have illustrated the formation of the mixed salt thickener at high temperatures, the thickener may also be prepared at lower temperatures of about 225 to 400 F. To illustrate, Example I is repeated but the mixture of oil, Hydrofol Acids 51, alicyclic acid and sodium hydroxide is heated to a maximum temperature of 250 F. until dehydrated.

Lubricating oils may also be thickened with a salt of the alicyclic acid as the sole thickener. For example, 20 Wt. percent of the calcium salt of the alicyclic acid of Example I is dispersed in wt. percent of the mineral lubricating oil of Example I.

What is claimed is:

-1. A lubricating grease composition comprising a major proportion of a lubricating oil and 5 to 40 wt. percent of a mixed-salt grease thickener comprising 3 to 15 moles of an alkaline earth metal salt of a low molecular weight aliphatic hydrocarbon monocarboxylic acid having about 1 to 6 carbon atoms per molecule, and one mole of an alkaline earth metal salt of an alicyclic monocarboxylic acid containing about 10 to 16 carbon atoms per molecule, formed by the alkali fusion of an unsubstituted, saturated cyclic ketone containing about 5 to 8 carbon atoms per molecule.

2. A grease composition according to claim 1, wherein said mixed-salt grease thickener also contains an alkaline earth metal salt of a fatty acid containing about 12 to 30 carbon atoms.

3. A composition according to claim 1, wherein said mixed-salt grease thickener also contains an alkaline earth metal salt of a straight-chain saturated aliphatic hydrocarbon monocarboxylic acid containing about 7 to 10 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 1,961,623 Pelton June 5, 1934 2,551,931 Currie May 8, 1951 2,801,974 Moiway et al Aug. 6, 1957 

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A LUBRICATING OIL AND 5 TO 40 WT. PERCENT OF A MIXED-SALT GREASE THICKENER COMPRISING 3 TO 15 MOLES OF A ALKALINE EARTH METAL SALT OF A LOW MOLECULAR WEIGHT ALIPHATIC HYDROCARBON MONOCARBOXYLIC ACID HAVING ABOUT 1 TO 6 CARBON ATOMS PER MOLECULE, AND ONE MOLE OF AN ALKALINE EARTH METAL SALT OF AN ALICYCLIC MONOCARBOXYLIC ACID CONTAINING ABOUT 10 TO 16 CARBON ATOMS PER MOLECULE, FORMED BY THE ALKALI FUSION OF AN UNSUBSTITUTED, SATURATED CYCLIC KETONE CONTAINING ABOUT 5 TO 8 CARBON ATOMS PER MOLECULE. 